I have a small portrait business, but still make plenty of posing errors. I like babies and toddlers best because you get what you get...there's no posing them! I have done a few seniors this summer and have had good feedback, so take my suggestions for what they are worth. I'm still learning too.
Your focus is great. You nailed the eyes all 4 times and I like the depth of field. I also think the 1st one is a little dark and agree that you could lighten it up in post processing. If you shot in RAW, it will be very easy. A slight levels adjustment will help with the dull contrast and make it pop more. Using a reflector or speedlight would have helped fill in the shadows too.
LOVE the 2nd one. I would like to see a little more of her fingers, but that's a minor problem because the lighting is so pretty.
I really like the pose of #3, but don't care for selective coloring. However, if the girl likes it, I wouldn't mess with it. A little more contrast will define her facial features a little better.
#4 is my least favorite. I do that pose a lot with teenage girls. You are coming from the right angle and did not give her "bunny ears" with her feet...that's good, but I wish I could see more of her arms and torso.
I think you did a great job!! Don't be afraid to try portraiture again.
